As shown on the right, a spreadsheet can be used to iterate to the answer.

Step 5: Calculate the new core size.
If the initial core size estimate without power straps is x,
then with power straps the core size becomes x′

x′ =

x

=

x

=

x

= x+4.71%

√(((1-ka2p)(1-ka3p))

√0.9552

0.955

The value 4.71% is called the IR Drop Adder.

The width of the power straps is set by the pitch,
strap allocation or width chosen by the user and the value of p
just calculated. An example is shown in the table below,
where we set the supply strap allocation to 5.5µm and compare
it to the old solution.

The new solution has allowed the power strap pitch to go up from
one every 88µm to one every 244µm.
The core side is 769µm less and the core area is 16% less
than the first solution, due to double bonding of supply pads,
tighter Vddmin spec and wider metal-5 straps.